Often times when a character dies in a TV series, it means the actor had a difference of opinion with the showrunner, or they were going on to another project and couldn't maintain their role. In Star Trek and other sci-fi shows, it just means it's another episode as there are a plethora of ways to bring a character back to life. Ensign Harry Kim in Star Trek: Voyager is proof of that alone.
For a grand total of four deaths, Garrett Wang's Ensign Harry Kim died more times than any other character on Voyager. Exploring an uncharted quadrant of the galaxy is dangerous, after all. Harry was an operations officer on Voyager's bridge who underwent some of the harshest situations compared to the rest of the crew. Despite showrunners denying him a much-deserved promotion and character development, Harry Kim remained a fan-favorite throughout the entirety of Star Trek: Voyager.
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"Emanations" (Season 1
In one of the first Harry Kim-heavy episodes of the series, the Starfleet ensign has his first brush with death. It's a good show of resourcefulness on Harry's part. Since Voyager traversed the unexplored Delta Quadrant, they were bound to come across many unknown aliens and rituals. "Emanations" shows the crew encounter an alien species known as the Vhnori and their burial grounds. The Vhnori people place the dying into a sarcophagus of sorts and transport them to the "next Emanation." This occurs through subspace vacuoles, but the Vhnori actually don't know where the bodies go. Voyager quickly discovers the vacuoles, as bodies spontaneously appear on the ship for as long as they're in close proximity to the burial site.
While exploring the burial site in a ring system, the away team decides to beam away so as not to disturb the site any more than they already had. During the beaming process, a new vacuole opens up and sends Harry to the planet where the bodies come from. As Harry learns all about the Vhorni customs and rituals, he also learns that they intend to keep him, to study since nobody has ever returned from the "next Emanation." Ensign Kim decides to switch places with a man named Hatil who is going to the next Emanation.
Upon Harry's successful return to Voyager, the Doctor performs an emergency resuscitation as the vacuole renders Harry dead. Lucky for Harry, the Doctor is very good at his job, but that wouldn't be Harry's only exploration in the afterlife.
"Deadlock" (Season 2)
Voyager doesn't waste time messing with temporal shifts or phase displacements. In fact, every time something weird happened to the ship and crew, it was because Captain Janeway decided to explore some peculiar anomaly. Season 2's 21st episode introduced Harry's most "permanent" death, so to speak. After unwittingly traveling through a time shift, the anomaly duplicates the Voyager ship and its crew, except they share the same antimatter core, causing all sorts of problems. To make things worse, Ensign Samantha Wildman gives birth to the first Federation child on Voyager and in the Delta Quadrant.
Both ships experience power failures and decide to expel proton bursts in order to compensate. This causes problems for both Voyagers. The burst from one Voyager severely damages the other and causes numerous hull breaches. The Harry Kim from what the audience would consider the Prime Voyager becomes an unfortunate victim to one of the breaches, as he's pulled into the vacuum of space.
Once the two Voyagers learn about each other's existence, they attempt to coordinate aligning their phase variances to become one again. Unfortunately, matters worsened, and the Janeway from the heavily damaged Prime Voyager decided that self-destructing was the only way one of the ships would survive. The organ-harvesting Vidiians throw a wrench in the whole plan, forcing the duplicate Voyager to initiate its self-destruct sequence instead.
Before the Vidiians successfully harvest organs from the entire bridge crew, Captain Janeway of the duplicate Voyager sends the Harry Kim from her ship, along with the newly born Naomi Wildman, to the Prime Voyager where he goes on to live the rest of his days. Technically speaking, the Harry Kim and Naomi Wildman who exist throughout the rest of the series aren't actually from the Prime reality.
"Timeless" (Season 5)
As the title of the episode suggests, time travel plays a major role in this story. Audiences get their first glimpse at an older Harry as the show takes a non-linear approach, jumping back and forth between two different timelines. In the past, Harry developed an experimental quantum slipstream drive for Voyager in an attempt to get the crew back to the Alpha Quadrant in record time. The plan was for Chakotay and Harry to fly in a shuttle ahead of Voyager in order to relay course corrections to Tom Paris to avoid a catastrophe. As the existence of a future Harry and Chakotay implies, such a catastrophe occurred.
A miscalculation on Harry's part caused the quantum slipstream drive to malfunction, sending Voyager out of the slipstream route and crashing into an ice planet. What was future-Harry's plan? Send a message to past-Harry with the accurate information and prevent the starship from ever crashing. Unfortunately, that's a breach of the Temporal Prime Directive, which puts Chakotay and Harry at odds with Starfleet.
While evading Starfleet and simultaneously send a message back to the past, the shuttle's warp core overloads and explodes, killing Harry and Chakotay. Harry, being the quick thinker and dedicated ensign that he was, successfully sent a message to past-Harry that instructed him how to remove the shuttle and Voyager from the slipstream and into normal space. They might not have gotten home any faster, but they still had their lives.
"Endgame" (Season 7)
This isn't the time to critique Voyager's ending. Well, maybe just a little bit. Much like "Timeless," Voyager's series finale "Endgame" sees a guilt-ridden Admiral Janeway use time travel to correct some wrongs that got her and her crew back to the Alpha Quadrant. Some wrongs that got Seven of Nine and Commander Chakotay killed. So, the elderly Admiral Janeway decides to use some Klingon technology to travel to the past. This puts Captain Harry Kim (hey, he finally got his promotion!) hot on her trail, as Starfleet aren't fans of time travel. By the time he catches up with his former Captain, the Klingons are also in pursuit because the technology she intends to use she stole.
It takes some convincing, but Harry eventually lets Janeway go. The last thing this Harry sees is Janeway disappear into a temporal vortex, where she eventually sacrifices herself to the Borg in order to get her crew home without any casualties. Harry doesn't die on screen in this case though, and his death is more metaphorical because he "died" with the rest of his timeline as Janeway erased it with her little time-traveling adventure.